Effects of vitamin D and calcium supplementation on bone mineral density among Thai youth using daily HIV pre-exposure prophylaxis

1 | INTRODUCTION Men who have sex with men (MSM) make up the largest population receiving new HIV diagnoses in the United States (87%) [1], a trend also seen in [...]
Introduction: Tenofovir disoproxil fumarate with emtricitabine (TDF/FTC) is used for HIV pre-exposure prophylaxis (PrEP). TDF may affect bone mineral density (BMD), particularly in youth who are at a stage of peak bone mass accrual. The objective of this study was to evaluate the effect of vitamin D and calcium supplementation on BMD among Thai youth receiving daily oral PrEP. Methods: This open-label randomized trial was conducted in male youth aged between 15 and 24 years. Participants were randomized to Arm A who received once-daily TDF/FTC plus vitamin D3 and calcium supplementation with meals twice daily (400 units of vitamin D3 and 1200 mg of elemental calcium/day) or Arm B who received once-daily TDF/FTC only. PrEP users were defined as taking at least two tablets/week (tenofovir-diphosphate level of >350 fmol/punch). Adherence to vitamin D/calcium supplementation was defined as self-reported adherence of >50%. Lumbar spine (L2-L4) BMD (LSBMD) was evaluated by dual-energy X-ray absorptiometry scan zero and six months after PrEP initiation. Results: From March 2019 to March 2020, 100 youth were enrolled. Baseline characteristics between the two arms were similar. Median (IQR) age was 18 (17 to 20) years. At entry median (IQR) LSBMD z-score was -0.8 (-1.5 to -0.3), 17% had low LSBMD (Z-score < -2). The median amount of calcium intake from nutritional three-day recall was 167 (IQR 94 to 272) mg/day 39% of participants had vitamin D deficiency defined as 25(OH)D levels 3% increase in LSBMD at month 6 compared to baseline (67.6% vs. 42.9% respectively; p = 0.03). There were significantly higher increases in LSBMD among youth with vitamin D deficiency who were supplemented; arm A + 0.05 (0 to 0.05) compared to arm B + 0.03 (-0.1 to 0.03), p = 0.04. Conclusions: Increases in LSBMD over six months among youth using PrEP who received vitamin D/calcium supplementation was greater than those not supplemented. Long-term follow-up should be considered to explore long-term outcomes. Keywords: HIV pre-exposure prophylaxis; young men who have sex with men; young transgender women; bone mineral density; vitamin D; calcium